Answer: c. a failure of memory consolidation.
Step-by-step explanation:
Retrograde amnesia is a kind of amnesia in which the loss of access to the memory occurs. The person forgets the information about the past events. It results due to the damage of the areas of the brain other than the hippocampus (part involved in encoding memories) like neurons and synapses (will be responsible for storing the long-term memories).
On the basis of the above information a memory consolidation failure is the correct option.